Gabble, if it gets an error presence back from the server, uses the text of the message as the contact's presence string, along with type=Error. Empathy just blindly shows that.

Vincent filed https://bugs.freedesktop.org/show_bug.cgi?id=46753 on Gabble, and said:

> The error could possibly be prefixed with something like "Server cannot find contact: %s".
> 
> The issue is really that those strings aren't clear as to whether the issue is in my client, between my client and my server, or between my server and the server of my contact. Those strings, as they are right now, just tell the user "you got some random error".

The spec says: <http://telepathy.freedesktop.org/spec/Connection_Interface_Simple_Presence.html#Enum:Connection_Presence_Type>

> Error, an error occurred while trying to determine presence. The message, if set, is an error from the server.

So I think the prefix Vincent suggests would be reasonable.